1. Technical Field
The present invention relates to a light emitting device, a super-luminescent diode, and a projector.
2. Related Art
A super-luminescent diode (hereinafter also referred to as an “SLD”) is a semiconductor light emitting element, which is capable of providing an output up to several hundreds of mW with a single element similarly to a semiconductor laser while having a broad spectrum and thus being incoherent similarly to an ordinary light emitting diode.
The SLD is used as, for example, a light source of a projector. For example, there has been proposed a system of a projector disposing each of the SLD for emitting red light, green light, and blue light immediately below a light valve, and simultaneously performing control of the emission angle of the light (collection, collimation, and so on) and uniform illumination using microlenses. It is desirable in such a projector to form two or more colors of light sources (out of the three colors) on the same substrate in order to achieve common use of the optical system for miniaturization and cost reduction of the projector.
For example, JP-A-2002-299750 discloses a technology of forming two semiconductor lasers with respective wavelengths on the same substrate.
By using the technology described above, it is possible to form the semiconductor lasers or the SLDs respectively having two colors of blue and green on the same substrate.
However, in the light emitting device described in the patent document mentioned above, an n-side electrode and a p-side electrode for injecting current into an active layer are formed on the both sides of the light emitting device across the active layer and the substrate. Therefore, there is a problem that the layout of the wiring lines to be electrically connected to the electrodes is made complicated and a higher mounting cost is required when mounting the light emitting device.